使用objc_setAssociatedObject为UITableViewCell传递UIButton @selector参数

Question

我正在尝试在本文中实现一个建议：使用objc_setAssociatedObject和objc_getAssociatedObject 将参数传递给选择器，以将@selector参数传递给UITableViewCell的UIButton 。 按照我的编码方式，它总是最终经过创建/加载的最后一个单元格所在的行。 这是我的代码：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    UILabel *mainLabel;
    soundButton=[UIButton buttonWithType:UIButtonTypeCustom];

    if (cell == nil){

        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    soundButton.tag = 33;
        [soundButton addTarget:self action:@selector(soundButtonAction) forControlEvents:UIControlEventTouchUpInside];
        [soundButton setFrame:CGRectMake(210,3,68, 37)];

         [soundButton setBackgroundImage:[UIImage imageNamed:@"musicNote"] forState:UIControlStateNormal];

         [cell.contentView addSubview:soundButton];
    } else {

        soundButton = (UIButton *)[cell.contentView viewWithTag:33];
    }
    objc_setAssociatedObject(soundButton, "IndexPath", indexPath, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    return cell;
}

-(void)soundButtonAction
{
    NSIndexPath *ip = objc_getAssociatedObject(soundButton, "IndexPath");

Answer 1

看起来soundButton是您班上的一个ivar？ 每次请求一个单元格时，它都会被覆盖，因此您只会获得最后一个单元格。

我也认为使用"IndexPath"作为键不是一个好主意。

static char indexPathKey; // use address of indexPathKey as key

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    UILabel *mainLabel;
    soundButton=[UIButton buttonWithType:UIButtonTypeCustom];

    if (cell == nil){

        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
    soundButton.tag = 33;
        [soundButton addTarget:self action:@selector(soundButtonAction:) /*extra :*/ forControlEvents:UIControlEventTouchUpInside];
        [soundButton setFrame:CGRectMake(210,3,68, 37)];

         [soundButton setBackgroundImage:[UIImage imageNamed:@"musicNote"] forState:UIControlStateNormal];

         [cell.contentView addSubview:soundButton];
    } else {

        soundButton = (UIButton *)[cell.contentView viewWithTag:33];
    }
    objc_setAssociatedObject(soundButton, &indexPathKey, indexPath, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    return cell;
}

-(void)soundButtonAction:(UIButton *)sender
{
    NSIndexPath *ip = objc_getAssociatedObject(sender, &indexPathKey);